Chemical interaction and ligand exchange between a [(CH3)3Si]3Sb precursor and atomic layer deposited Sb2Te3 films

Abstract

The chemical interaction between the [(CH₃)₃Si]₃Sb precursor and atomic layer deposited Sb₂Te₃ thin films was examined at temperatures ranging from 70 to 220 °C. The trimethylsilyl group [(CH₃)₃Si] displays greater affinity for Te than for Sb, and this drives replacement of Te in the film with Sb from the [(CH₃)₃Si]₃Sb precursor, while eliminating volatile [(CH₃)₃Si]₂Te, especially at elevated temperatures. The compositions of the resulting Sb–Te layers lie on the Sb₂Te₃–Sb tie line. The incorporation behavior of [(CH₃)₃Si]₃Sb was explained in terms of a Lewis acid–base reaction. The exchange reactions occurred to relieve the unfavorable hard–soft Lewis acid–base pair between the trimethylsilyl group and Sb in [(CH₃)₃Si]₃Sb. Such a reaction could be usefully adopted to control the chemical composition of ternary Ge–Sb–Te thin films.